With the increased emphasis on fuel economy and reduced exhaust emissions, various procedures and methods of increasing the efficiency of internal combustion engines and reducing the exhaust emissions thereof are being tested and evaluated. However, most air and fuel induction systems which may be efficient at one operating temperature are inefficient at other engine operating temperatures. Various types of structures have been incorporated into air and fuel induction systems designed to promote fuel economy and reduce exhaust pollution, but many of these have proven ineffective, at least to some degree.
Examples of previously patented air and fuel charge forming devices may be found in U.S. Pat. Nos: 3,789,817; 3,765,382; 3,738,334; 3,728,856; 3,699,938; 3,667,436; 3,618,579; 3,554,174; 3,496,919; 3,354,872; 2,748,758; 2,461,411 and 2,205,750.